
One of my boys never achieved a tie - he didn't have that many bitches (on purpose!) and he was always held in but he only missed to one - she came back to my other proven stud dog (tie) a year later but again missed. She was taken to another stud dog, proven, but missed again. Clearly all this was not the fault of the stud dogs. I know most breeders prefer to see a tie, but my dog suggests that it's not totally necessary.
I didn't do scans, preferring to wait and planning for a litter. If mine went over by more than 2 days, they were seen by my vet, and if it was obvious they were in whelp, given a shot to get them started. If it was not certain they were pregnant, x-ray was done to confirm what was going on before they were given a shot. Scans are not accurate, and only confirm, or not, a pregnancy at the time of the scan. Even if a scan said no, I'd still be waiting until the due date